Green synthesized CuI as an adsorbent and a photocatalyst in the removal of aqueous reactive red 256 & reactive black 5 dyes

Abstract

The extensive utilization of dyes in the industries and the consequent generation of their effluents in the water bodies have posed a major risk to the environment and mankind. Therefore, there is an increased necessity for waste water treatment in textile industries. The present study involves the utilization of highly versatile copper (I) iodide synthesized using Hibiscus rosa-sinensis L. flower extract (CuI-FE) in the removal of textile dyes. The synthesized material was characterized using XRD and found to be highly crystalline with an average crystallite size of 89.01 nm. The average particle size of the agglomerated CuI-FE was measured to be 492.7 nm using HR-SEM. The d-spacing calculated from HR-TEM was found to match with that from XRD. XPS analysis confirmed the oxidation state of Cu(+1) in CuI-FE. The purity of the syntheised CuI-FE was ascertained from its EDAX data. It was further characterized using BET, FTIR and UV-Visible spectroscopic techniques. Batch adsorption studies of Reactive Red 256 (RR) and Reactive Black 5 (RBL) were probed in the presence of CuI-FE and the respective adsorption capacity of RR and RBL were found to be 135.22 and 176.42 mg/g. LCMS data taken of the solution after Batch adsorption studies at the end of 24 h showed the presence of intermediates of low molecular weight that are environmentally benign confirming that the initial adsorption process was followed by degradation of dyes. A possible dye degradation pathway was proposed using LCMS data analysis.